This invention relates generally to wind turbines and, more particularly, to a dual rotor wind turbine that is more efficient than its predecessors and can produce multiple forms of power.
People have used the wind as a power source for years. Initial uses included pumping water and grinding flour. With the discovery of electricity and the invention of the generator, windmills have been designed to generate electric power. For a long time, however, a cheap and abundant supply of fossil fuel has powered much of the world. Unfortunately, this supply of coal and oil is limited, requires extensive energy to extract, and creates vast amounts of pollution when combusted. These concerns have led to a new interest in renewable clean energy. Wind energy can solve these problems of pollution and offer an unlimited supply of energy. A wind turbine with an efficient design can offer competitive energy prices compared with traditional ways of generating power. Once the initial capital investments are made, the wind turbines require minimal attention and minimal maintenance.
Traditionally, wind turbines use a single rotor to capture the kinetic energy of the wind. While dual rotor wind turbines are known in the art, such as in U.S. Pat. No. 4,039,848, U.S. Pat. No. 5,506,453, and U.S. Pat. No. 6,278,197, these wind turbines employ counter-rotating propellers to jointly produce a single power output. Further, the propellers are often of a single size and do not maximize the harvesting of all available wind energy.
The airstream after the first rotor on a wind turbine is moving slower than the airstream before the first rotor because the rotor extracts power from the kinetic energy of the wind. This means that the airstream is wider after the rotor. In order to harness this wind and the additional wind that is passing through the first rotor, the second rotor should be larger.
Further, there is an unmet demand to produce multiple forms of power, such as different voltages or combinations of either AC or DC electrical power, or to operate multiple combinations of generators, pumps, and compressors from a single wind turbine.
Therefore, it is desirable to have a dual rotor wind turbine that efficiently harnesses the kinetic energy of the wind, can produce multiple outputs, can be easily manufactured, and will suit a wide variety of wind speeds.